In order to address the issue of increasing bandwidth requirements demanded for wireless communication systems, different schemes are being developed to allow multiple user terminals to communicate with a single base station utilizing the same shared single channel or multiple channels.
A multiple-input multiple-output (MIMO) wireless system employs a number (NT) of transmit antennas and a number (NR) of receive antennas for data transmission. A MIMO channel formed by the NT transmit and NR receive antennas may be decomposed into NS spatial streams, where, for all practical purposes, NS min {NT,NR}. The NS spatial streams may be used to transmit NS independent data streams to achieve greater overall throughput.
In wireless networks with a single Access Point (AP) and multiple stations (STAs), concurrent transmissions may occur on multiple channels toward different stations, both in the uplink and downlink direction. However, each STA may be capable of transmitting or receiving in only one channel at a time, while the AP is typically capable of transmitting or receiving concurrently on multiple channels. One challenge in such systems is to allocate STAs to operate (transmit and/or receive) on different channels in a manner that achieves acceptable performance, in terms of load balancing and/or some other consideration, such as Quality of Service (QoS) targets.